Multistage amplifier circuits



June 19, 1923. 1,459,419

E. O. SCRIVEN MULTI STAGE AMPLIFIER CIRCUITS Filed April 30 1919 AAAllllA IvvvvVII [aw ma d (So /lye To all am a may mm.-

7 siding Patented June 19, 1923..

UNITED STATES PATEN oFFIcE.

EDWARD O. SCRIVEN, OF NEW YORK, N. Y., ASSIGNbR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF

NEW YOBK, N. Y., A-CORPOBATION OF NEW YORK.

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Application filed April 80, 1919. Serial No. 293,872.

Be it known that I EDWARD O. SCRIVEN, a citizen of United tates of America re- York, State of New York, have invented certain new and useful Improvements in Multistage Amplifier Circuits, of which the following is a full, clear, concise, and exact description.

-. This invention relates to multi-stage am plifier circuits and more particularly it relates to vacuum tube circuits .wherein a plurality, of repeaters or. amplifiers are emplloyed to amplify signals impressed thereon om an incoming line.

.- One of the objects of this invention is to provide a means for regulating the degree of amplification of a multi-stage amplifier set for signals impressed thereon.

As is well known in the art, Weak currents or signals may be amplified to any desired degree by impressing them on a plurality o vacuum tube amplifiers arranged to work into each other by suitable circuit connections. In employing such a multistage amplifier set for. amplifying weak currents, it is frequently found undesirable of amp use the total'amplification of the set before impressing single switching means is employed to cut in or out one or more of the plurality of the am lifiers so as to regulate the amount ification for any givencase. An additional switch. is also provided for regulating the strength of the currents impressed on the first tube so that by operatin both switches any desired degree of ampli cation from theset may be obtained.

This invention will be better understood by reference to the following detailed de-' scription taken in connection with the accompanying drawing which represents one embodiment of this invention applied to a multi-sta e amplifier set for varying the degree 0 amplification obtained therefrom.

at New York, in the county of lVew trodes 14, 15,

Referring to the drawing 5, 6 and 7 are vacuum tube amplifiers containing cathodes, 8, 9, 10, anodes 11, 12, 13 and control elec- 16, respectively. Heating current for the three filaments is supplied from battery 18. Output-circuit current for the three tubes is supplied by battery 19. The

output circuit for tube 5 may be traced from anode 11-, through wire 20, resistance 21,

which may be non-inductive or inductive battery 19 to cathode 8. The output circuit for tube 6 may be traced from anode 12, wire 24, resistance 25 which may benoninductive or inductive, battery 19 to cathode 9. The output circuit for tube 7 is completed only when the rotary switch 27 has put circuits of the other tubes; and when the contact arm 27 is on contact 32 the output transformer is connected only in the ouiput circuit of the second tube.

t follows therefore that if only one stage of amplification is desired for impulses impressed on tube 5 by the input transformer 34, contact arm 27 should be on contact 31 so that the amplifying impulses in the output circuit ofthe first tube 5 will be impressed througlh transformer 30 to the outgoin line. f, however, two stages of amp ification are desired, contact arm 27 should be moved to contact 32 so that the amplified impulses in the output circuit of tube 5 will be impressed on the input terminals 15 and 9 of tube 6 for further amplification by tube 6 before being impressed on the output transformer 30, which is in the output circuit of tube 6 when contact arm 27 is on contact 32. Similarly, if three stages of amplification are desired, the arm 27 should'be moved to contact 28 thereby putting the above transformer in the output circuit of thethird tube 7; With this ciricuit connection the impulses that have been I 1ts contact arm on contact 28, and may be I induce tit number of amplifiers connected between the input and output transformers of the set. It sometimes may be desired to get a more accurate adjustment of the strength of the amplified currents desired for a particular incoming impulse than is obtainable by cutting in or out one or more of the stages. Such an adjustment may be obtained by the use of a switch 37 adapted by a plurality of contacts to vary the efiective number of turns in the primary winding 38 of transformer 34. Thus when contact arm 37 is on contact 39, all the turns in the primary winding 38 are in the circuit with the incoming line while when the contact arm is on contact tO, for example, only a few turns of the primary winding are effective.

The manner in which the switch 37 may be employed in connection with switch 27 to control the strength of the amplified currents in the secondary winding of trans former 30, may be illustrated as follows: The winding 38 has taps brought out at various points to adapt it most efiiciently to the partlcular line to which it is connected, since the greater the impedance of the line the reater should be the impedance of the win in in order to get maximum voltage in the secondary winding of the transformer. Suppose, for example, that winding 38 is connected up with a line of such an impedance that the line should be connected to the total number of turns of winding 38 for most efficient operation. Let it be further assumed that, for an incoming impulse of a given strength and with switch 37 on contact 39, one stage of amplification gives a smaller value of the amplified current than is desired and a two-stage amplification gives a greater value of the amplified current than is desired. The switch 27 should then be placed on contact 32 for two stage amplification and the strength of the amplified current cut down by moving switch 37 to cut out a part of the primary coil 38 until the desired strength is obtained.

In the preferred form of this invention the vacuum tubes inserted between the incomin and outgoing lines should all be ampli ers so as to impress on the outgoing line impulses similar to those received except amplified in form, but this invention is in no wise limited thereto.

It is obvious that this invention is not limited to a multi-stage amplifier set containing three stages, but may be employed in systems containing any number of stages desired. It is also obvious that this invention is not limited to the particular means shown for having the output circuit of one tube work into the input circuit of a second tube. It is well known in the art that this connection may be made in a variety of ways. It is furthermore to be understood that the phrase vacuum tubes as used in this specification and the appended claims, is intended to be readable on gas filled tubes as well as those completely evacuated.

What is claimed is:

1. A multi-stage amplifier set comprising a plurality of electric discharge amplifiers and switching means for providing a unified control-0f said amplifiers whereby the number of effective stages of amplification of said set may be varied.

2. A multi-stage amplifier set comprising a plurality of electric discharge amplifiers, and switching means for providing a unified control for cutting in or out a plurality of said stages.

3. A vacuum tube set comprisingaplurality of vacuum tubes, input terminals for said set, output terminals for said set, switching means for associating said output terminals with any one of a lurality of said tubes, and means for re ulhting the amount of input voltage supp ied to one of said tubes.

4. A multi-stage amplifier set comprising input terminals for said set, output terminals for said set, a plurality of vacuum tube amplifiers, each having an output circuit and switching means for associating said output terminals with any one of the output circuits of a plurality of said amplifiers.

5. The combination of a vaccum tube set comprising a plurality of vacuum tubes, each having an output circuit, means for impressing current impulses upon said set, an outgoing line, means for impressing the amplified current impulses .upon said line, switching means named means in circuit with any one of the output circuits of a plurality of said tubes,

and means for regulating the input voltage supplied to one of said tubes.

6. A multi-stage amplifier set comprising a plurality of vacuum tube amplifiers each of said amplifiers, having an output circuit, and means for varying the efiective amplification of said set comprising a single switch adapted to be connected to any one of a plurality of said outputcircuits.

7. A multi-stage amplifier set comprising a plurality of amplifiers each having electrodes, means for varying the number of effective stages of amplification of said set, said means comprising a switch having a plurality of contacts, and electrical connections from each of said contacts to an electrode of one of said amplifiers.

8. A multi-stage amplifier set comprising a plurality of amplifiers each having a cathode, and an anode, means for varying the number of effective stages of amplification of said set, saidmeans comprising a switch having a plurality of contacts, and electrical connections from each of said contacts to. the anode of one of said am lifiers.

9. A multi-stage amp er set comprising for connecting said second a pluralit of amplifiers, means for providing a uni ed control for cutting in or out a plurality of said stages, and means for regulating the amount of input voltage supplied to one of said amplifiers.

10. A multi-stage amplifier set comprising a plurality of vacuum tube amplifiers, means for providing a unified control for cutting in or out a plurality of said stages, and means for regulating the amount of input voltage applied to the first stage of said set.

11. A multi-stage amplifier set comprising output terminals for said set, a plurality of vacuum tube amplifiers each having an output circuit, means for associating said output terminals with any one of the output circuits of a, plurality of said amplifiers, means for impressing impulses on the first of said stages, and means for regulating the effectiveness of said impressing means.

12. A multi-stage amplifier set comprising a plurality of amplifiers each having electrodes, means for varying the number of effective stages of amplification of said set, said means comprising a switch having a plurality of contacts, electrical connections from each of said contacts to an electrode of one of said tubes, an input transformer for said set, and means for varying the number of efi'ective turns of a primary winding of said transformer.

13. A multi-stage amplifier set comprising a plurality of amplifiers each having a cathode, and an anode, means for varying the number of effective stages of amplification of said set, said means comprising a switch having a plurality of contacts, electrical connections from each of said contacts to the anode of one of said tubes, an outgoing line, a transformer between said line and said amplifiers, said switch having a movable contact in circuit with the primary winding of said transformer, said movable contact being adapted to engage said first mentioned con tacts.

14. The combination of an incoming line, an outgoing line a plurality of amplifiers therebetween connections and a switch contact which in one position connect one of said amplifiers between said lines and which in another position connect a plurality of said amplifiers between said lines.

15. The combination of an incoming line, an outgoing line a plurality of vacuum tube devices adapted to be connected in tandem therebetween, connections and a switch contact which in one position connect oneof said tubes to the exclusion of another between said lines and which in another position connect a plurality of said tubes in tandem between said lines.

16. The combination of two lines, a plurality of vacuum tubes adapted to be connected in tandem therebetween, switching means for connecting (a) one tube between said lines, (6) two tubes in tandem between said lines, or (0) three tubes in tandem between said lines.

17. The combination of two lines, a plurality of vacuum tubes adapted to be connected in tandem there-between, a switch and connections controlled thereby, said switch in one position connecting one tube between said lines, in another position connecting two tubes in tandem between said lines and in a third position connecting three tubes in tandem between said lines.

In witness whereof, I hereunto subscribe my name this 24th day of April, A. D. 1919.

EDWARD O. SCRIVEN. 

